1. Field of the Invention
The invention relates in general to a technique for determining the memory type, and more particularly, the invention relates to an automatic determining mechanism of a motherboard that support various types of memories.
2. Description of the Related Art
Dynamic random access memory (DRAM) plays an important role in the field of personal computers. As techniques develop and cost is reduced, the types and capacity of the dynamic random access memory continuously progress. The most popular dynamic random access memory on the market includes the synchronous dynamic random access memory (SDRAM). Inevitably, the SDRAM is replaced as technique progresses. Currently, the double data rate dynamic random access memory (DDR DRAM) is the representative product of the next generation. However, as the technique is not fully developed yet, it is still too expensive. Therefore, in the transition time of two generations, a motherboard that accommodates both the SDRAM and the DDR DRAM is produced in personal computer industry. The operation voltage such as I/O supply voltage for the DDR DRAM is 2.5V, while the operation voltage for the SDRAM is 3.3V. The mixed DRAM motherboard provides the jumper to let the user to configure the type of DRAM. However, this confuses the user and easily causes manmade mistake in operation, consequently damaging the equipment. Therefore, a mechanism to automatically determine the type of DRAM is necessary.
Currently, most computer systems provide several power saving modes like suspend to RAM (STR) mode or suspend to disk (STD) mode. No matter the computer system is reset or rebooted after soft off, mechanical off, or STD mode, the mixed DRAM motherboard must have a mechanism to redetect the type of DRAM. When the computer system enters the STR mode, the motherboard has to maintain a configured operation voltage to prevent memory from data loss or from damage.